Fagor alarm 3738: The axis has moved while the CNC was off

What it means

At power-up the absolute coordinate stored in the drive does not match the coordinate saved at the end of the last session, differing by more than parameter MAXDIFREF. Since absolute feedback should remember position across power cycles, the mismatch suggests real movement or a feedback integrity issue.

Likely causes

• axis physically moved (crash, manual push, thermal drift) while powered down
• absolute encoder battery dead allowing position memory loss
• drive feedback initialization problem corrupting the stored coordinate
• MAXDIFREF set tighter than normal machine behavior requires

Replacement parts

We supply the following units for this alarm — tested, warranty-backed:

• Absolute linear scale SA / GA series

  scale · Common cause

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• Encoder battery (scale/drive backup cell)

  encoder · Common cause

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